A check valve provided at a drain funnel (a floor drain funnel) has been known as disclosed in, e.g., Japanese Patent Publication No. 2013-185386. The drain funnel is provided on, e.g., a floor of a factory, and is for discharging, to the outside, fluid such as contaminated water spilled or discharged over a floor surface. The drain funnel includes a storage tank (a recess) buried on the floor, and a discharge pipe (a water discharge pipe) provided at a bottom portion of the storage tank. In addition, the check valve is provided at the discharge pipe. The check valve includes an annular valve seat member, a spherical float, a plurality of guide rods (support bolts), and support members. The guide rods are arranged at the periphery of the float, and are configured to guide upper-to-lower movement of the float. The support member is provided at a lower end portion of each guide rod, and is configured to constrain the lower position of the float. When fluid flows back in the discharge pipe, the float is, in the check valve, lifted (floated) by the fluid, and then, seats on the valve seat member. In this manner, the backflow of the fluid is reduced or prevented. In other normal states than the backflow state, the float is unseated from the valve seat member, and is supported by the support members. With this configuration, e.g., the fluid discharged over the floor surface flows into the storage tank, and then, is discharged through the discharge pipe.